Laminated structure



May 22, 1945. R, v BOYER 2,376,653

LAMINATED STRUCTURE Filed March 31, 1942 LAN/NATED RES/N IMPRESNATED ANDCIMTED SHEET 0R BlD THERMSET RESIN /N CELLULAR FORM LHM/NATED RES/NIMPREGNATED IND CATED .SHEET 0R B17/#RD THERMSET RES/N /N CELLULAR FRMSPACE/f5 F THERMSET RES/N, WMD, ETC.

Inventor:

Ralph Boyer His Motor-neg.

Patented ,May 1945 vUNITED STATES PATENTl OFFICE LAMINATED STRUCTURERalph V; Boyer, Nahant, Mass., assignor to General Electric Company, a

York

corporation o! New Application ivm-ch si, 1942, serial No. 436,926

Other objects will be apparent from the descrip-V tion of the invention.

In the drawing Figure 1 shows va, view in elevation of one form of myinvention while Figure 2 shows a modification.

It has heretofore been suggested that lightweight porous structuresv maybe produced' by using rubber or other lthermoplastic material incellular or porous form or by causing an agent such as a gas to producea cellular structure in the' material. Certain thermoplastic materials,such as cellulose esters, have, been suggested for use as base materialwith a gas forming salt to produce the porous structure. As far as I amaware, all these prior suggestions involving thermoplastic materials, donot give products of sufiicient rigidity and strength coupled withvlight- In accordance with my invention laminated structures of excellent`rigidity and strength and relatively thick cross-sectional area may beproduced while at the same time maintaining lightness in weight.

One method by which the products of my invention may be produced is asfollows:

A laminated material, such as a fibrous sheet or sheets bonded with athermoset resin, is placed in an ordinary platen press. Between thissheet and another is placed a thermosetting resin, in either the liquidor solid state, the resin being in a convertible stage. The side of eachsheet facing the resin may be sanded to improve the bond between thesheets and resin foam. The press is closed. the closing being limited bystops surrounding the laminating material and resin so as to confine theresin between the sheets. Heat is applied and the uncured resin isallowed to fuse, foam and form a cellular structure, forcing thelaminating sheets against the press platens. Ordinarily no gas producingor foaming agent is necessary but may be added Vto the resin beforemaleate-ethyl methacrylate resins, polypropyl maleate-vinyl acetateresins, methyl methacmolding, particularly in large sections where it 55may be necessary to control the uniformity of the cellular spaces. Assoon as the resin is cured to the infusible state the laminatedstructure may be removed from the press. Figure 1 shows a cross-sectionof the finished product which is hard, rigid and light in weight,

The strength of the product may. be increased by' adding to the resinouscomposition between the laminating sheets small percentages of fillersor reinforcing materials such as matted fibrous materials examples ofwhich are sisal, cocoanut shell bres, wood excelsior, etc. It has beenfound that such a mat reinforces the structure and keeps the laminatedsheets apart and against the platens during the curing operation. Thepercentage of reinforcing agent can be varied and it has been found that10 to 15% is ian excellent a percentage to use.

Sheets of large area may be used to produce large size products and tooffset any tendency to buckle or warp, spacers are placed between thesheets as shown in Figure Z of the drawing.

,These spacers may be of any suitable material,

e. g., wood, laminated synthetic thermosetting resin impregnatedmaterial, etc., and form an integral part of the finished product.

Various thermosetting resins may be used in producing the products of myinvention. Among those which may be used are thermosetting resins of thephenol-aldehyde type, urea-aldehydetype and various thermosettingresinous compositions such as, phenol formaldehyde-protein resins,phenol formaldehyde-polyvinyl formal resins, phenolformaldehyde-polyvinyl alcohol resins, phenol formaldehyde-glycerineresins, phenol formaldehyde-urea resins, phenol formaldehydemelamineresins, phenol formaldehyde-diazine resins, phenol furfural resins,phenol furfural formaldehyde resins, triazine formaldehyde resins,benzene disulphonamide-acrclein resins. melamine dicyandiamide resins,polyethylene rylate-glycol methacrylate resins, polyvinylchloridedia1lyl succinate resins, styrene-divinyl benzene resins, etc.

The percentage of resin need not .be high t0 produce satisfactoryproducts. It will vary with the size of the product and the intendeduse. The most desirable resin content of theporous space is about 30% byvolume. Percentages as low as 10 and 15% produce a very Weak structure,while higher resin percentages give some increase in strength coupledwith increase in density and cost of the product. The optimum a producthaving the best combination of properties.

One of the principal advantages of my uwen. tion is the facility withwhich structures of large area may be produced. Such structuresl are ofhigh strength and rigidity coupled with relative lightness in weight.

Thus. in accordance with the present invention it is possible to producelaminated structures having a specinc gravity of the order of forexample 0.7 in a V4" board where the resin content averages about 32% byvolume, the filler or reinforcing agent averages about 11% by volume andthe air space averages about 57% by volume. the flexural strength of theproduct averaging from about 4.700 pounds -per square inch to about i7,800 pounds per square inch.

Moreover. it is possible to produce structures oi' relatively thickcross-sectional area. thin structures oder no dimculty in formation lithas heretofore been a diilicult problem to produce large. strong. rigidstructures of porous or cellular material of thick cross-sectional area.The products of my invention lend themselves Patent No. 2,576,655.

While asvaoss -resin percentage is to 53% by volume to give for use asinsulating board material, decorative panel material. refrigeratorcabinet construction and various other uses.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

A rigid, mechanically strong, lightweight 1aminated structure comprisingspaced sheets of laminated fibrous material containing a thermosetsynthetic resinous composition, an infusible, insoluble cellularsynthetic resinous composition surrounding and coating a resilient.matted reinforcing ller material between said spaced sheets and spacersof thermoset synthetic resinous composition between the inner surfacesof said spaced sheets forming an integral part of said laminatedstructure, the percentage by volume oi' synthetic resinous compositionbetween the spaced laminated sheets being about 30% and the percentageby volume of the reinforcing ller `material being about l0 to 15%, ltheiiexural strength of said laminated structure4 in '/4" thicknessaveraging from about 4,700 pounds per square inch to about 7,600 poundsper 4square inch.

f RALPH V. BOYER..

Hay 22. 1916.

ALPH v. Borsa.

It is hereby certified that error appears. in they printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line l, for to 55%" read Y5O to 55%--g and that thesaidjLetters Patent should be read with this correction therein that thesame may conform to therecord of the case in the Patent Office.

lsigned and sensa this 21st day of August, A. D. i9ii5.

(Seal) ALeslie Frazer First Assistant Commissioner of Patents.

a product having the best combination of properties.

One of the principal advantages of my uwen. tion is the facility withwhich structures of large area may be produced. Such structuresl are ofhigh strength and rigidity coupled with relative lightness in weight.

Thus. in accordance with the present invention it is possible to producelaminated structures having a specinc gravity of the order of forexample 0.7 in a V4" board where the resin content averages about 32% byvolume, the filler or reinforcing agent averages about 11% by volume andthe air space averages about 57% by volume. the flexural strength of theproduct averaging from about 4.700 pounds -per square inch to about i7,800 pounds per square inch.

Moreover. it is possible to produce structures oi' relatively thickcross-sectional area. thin structures oder no dimculty in formation lithas heretofore been a diilicult problem to produce large. strong. rigidstructures of porous or cellular material of thick cross-sectional area.The products of my invention lend themselves Patent No. 2,576,655.

While asvaoss -resin percentage is to 53% by volume to give for use asinsulating board material, decorative panel material. refrigeratorcabinet construction and various other uses.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

A rigid, mechanically strong, lightweight 1aminated structure comprisingspaced sheets of laminated fibrous material containing a thermosetsynthetic resinous composition, an infusible, insoluble cellularsynthetic resinous composition surrounding and coating a resilient.matted reinforcing ller material between said spaced sheets and spacersof thermoset synthetic resinous composition between the inner surfacesof said spaced sheets forming an integral part of said laminatedstructure, the percentage by volume oi' synthetic resinous compositionbetween the spaced laminated sheets being about 30% and the percentageby volume of the reinforcing ller `material being about l0 to 15%, ltheiiexural strength of said laminated structure4 in '/4" thicknessaveraging from about 4,700 pounds per square inch to about 7,600 poundsper 4square inch.

f RALPH V. BOYER..

Hay 22. 1916.

ALPH v. Borsa.

It is hereby certified that error appears. in they printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line l, for to 55%" read Y5O to 55%--g and that thesaidjLetters Patent should be read with this correction therein that thesame may conform to therecord of the case in the Patent Office.

lsigned and sensa this 21st day of August, A. D. i9ii5.

(Seal) ALeslie Frazer First Assistant Commissioner of Patents.

